1. Field of the Invention
The present invention relates to a one-way clutch of the type using rollers.
2. Description of the Related Art
In a conventional one-way clutch, cam faces for forming wedge-shaped spaces are usually formed in the inner circumference of an outer ring. This outer ring is made of induction-quenched steel and the rollers are made of bearing steel. It usually follows that the hardness of the cam faces of the outer ring and the hardness of the rollers are substantially equal.
When the aforementioned one-way clutch is used for high-speed rotations, for example, the rollers are repeatedly locked or freed, slipping may occur. With this slipping, over the useable life of the one-way clutch, both the cam faces and the rollers experience significant wear. The continuous progression of wear experienced by the cam faces, the wedge angle of the wedge-shaped spaces, as formed by the cam faces, gradually changes so thus causing a reduction in the clutch function. This reduction in the functionality of the clutch is exemplified by the unstable locked or freed actions.
Therefore, a main object of the invention is to provide a one-way clutch capable of stabilizing the roller locking and freeing actions for an extented life period of the one-way clutch.
The other objects, features and advantages of the invention will become apparent from the description to be made in the following.
According to the invention, there is provided a one-way clutch comprising: an inner ring member; a plurality of rollers arranged between the inner ring member and an outer ring member; and a retainer arranged between the inner ring member and the outer ring member for retaining the rollers individually, wherein the inner ring member has cam faces formed individually at a plurality of circumferential portions of the outer circumference thereof for forming such wedge-shaped spaces between the outer circumference of the inner ring member and the inner circumference of the outer ring member as are narrowed in one circumferential direction, wherein the rollers are individually arranged in the wedge-shaped spaces, wherein said retainer has a pocket defined therein, said pocket formed by a wall portion having an oblige part which extends therefrom, and wherein the cam faces are made to have a higher hardness than that of the rollers.
Preferably, the one-way clutch may further comprise: pressure members for pushing the rollers to the narrower sides of the wedge-shaped spaces.
Preferably, the retainer has pockets for accommodating the rollers, and the cam faces are formed in the regions corresponding to the pockets.
Preferably, the rollers are made of bearing steel, and the inner ring member, is made of induction-quenched steel including its cam faces and hardened on at least its cam faces to give the cam faces a higher hardness than that of the rollers.
Preferably, the cam faces have an HRC hardness of 65 or more whereas the rollers have an HRC hardness of 60 to 64.
According to the invention, the wear of the cam faces is suppressed even as the use of the one-way clutch progresses over time.
Therefore, the wedge angle of the wedge-shaped spaces can be held substantially constant independent of the extended time of the one-way clutch. If the wear of the rollers should occur, the rollers can be stably locked and freed because their biting actions into the narrower sides of the wedge-shaped spaces are unvaried.
Since the cam faces for forming the wedge-shaped spaces are formed on the outer circumference of the inner ring member, on the other hand, the roller positions are unvaried even if the rotating centrifugal force acts on the rollers to push them onto the inner circumference of the outer ring member. Therefore, the clutch function can be stabilized for a longer time period.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.